The present invention relates to the construction of portable wireless communication devices, and in particular to portable wireless communication devices for communicating through orbital satellites.
Prior art satellite terminals are large and expensive. For example, a terminal conforming to the standards known as INMARSAT-M is about the size of a small suitcase and costs approximately $10,000 in 1993. Such a terminal comprises a deployable directional antenna that has to be pointed to the satellite with no intervening obstruction in the line-of-sight, a telephone handset, and a box of electronics and batteries which is coupled to the antenna and to the handset by wires.
Cordless telephones are well known in the domestic context, and allow a user more freedom of movement than conventional telephones. Cellular telephones extend the benefits of wireless communications over wide areas, and can be used in moving vehicles. U.S. Pat. No. 5,428,668 describes an inventive combination of cellular and cordless phone technology which allows the same, cellular handportable telephone to be used both in the wide-area, mobile context, and as a home cordless phone. In addition, the telephone can receive calls either via the cellular system or via the normal home telephone system. In the latter case, the calls are translated to low-power cellular telephone call signals which can be broadcast using the same frequency bands as the wide-area cellular system without causing interference.
The above systems do not disclose translating calls from a satellite communications system into low power cellular call signals in order to receive them using a normal cellular handset.
U.S. Pat. No. 5,745,523 discloses a dual-mode cellular phone capable of operating in an analog FM mode or alternatively in a TDMA Digital speech mode, by using alternative signal processing programs in a programmable digital signal processor. In both cases, the FM or TDMA signal to be processed is received over the air using the same radio hardware.
U.S. Pat. No. 5,535,432 and entitled xe2x80x9cDual-Mode Satellite/Cellular Phone With A Frequency Synthesizerxe2x80x9d describes a dual-mode satellite/cellular telephone that comprises a satellite RF processing section, a cellular RF processing section, and a common signal processing section that can operate to process either satellite or cellular signals. This device locks preferentially to landcellular signals, if available, and if not, alternatively to satellite signals.
The systems described above, however, do not describe a dual-mode satellite-cellular phone comprising a cellular handset adapted to interface with a satellite adapter unit, wherein said handset receives signal for processing from said adapter unit by means of suitable cables.
It is an object of the present invention to provide a dual-mode telephone with a satellite communication adapter. According to one embodiment of the present invention, a cellular-type handportable phone is equipped with a connector for the attachment of accessories. According to the present invention, this connector provide a satellite communications adapter accessory access to the handset""s signal processing resources which may operate in an alternative mode to process signals received from the satellite and converted by the adapter into a suitable form for processing. The processing translates said satellite signals into voice or data, and vice-versa.
The present invention provides a number of options. First, the present invention provides a low cost option involves omitting landcellular-related components from the handset to provide the lowest cost satellite-only communications device. A second option comprises a second adapter similar to that described in U.S. Pat. No. 5,428,668 and entitled xe2x80x9cHome Base Stationxe2x80x9d, which is incorporated herein by reference, additionally equipped with the interface to the satellite adapter. This adapter translates received satellite signals into cellular-type signals which are rebroadcast for reception by the handportable cellular phone, and vice-versa. A third option comprises connection of said xe2x80x9cHome Base Stationxe2x80x9d also to the Public Switched Telephone Network via a normal telephone jack outlet, such that calls received either via the satellite or via the PSTN are translated into cellular-type or wireless calls to the handset.
According to one embodiment of the present invention, a dual-mode telephone device for communicating either through an orbiting satellite or through a landcellular system is disclosed. The telephone device includes a cellular telephone unit adapted for communicating in a cellular telephone network and further adapted to generate and to process digitized signals corresponding to transmissions to and from said satellite. In addition, the telephone device comprises satellite communications adapter means for receiving signal transmitted by the satellite and converting them to said digitized signals for processing by the cellular telephone unit and for receiving said digitized signals from said cellular telephone unit and converting them to transmissions to the satellite.
According to another embodiment of the present invention, a satellite communications adapter means is disclosed. The adapter means comprises directional antenna means and means for pointing said directional antenna means toward an orbiting satellite. Transmit-receive connection means connect the antenna to receiving and transmitting circuits. The adapter further comprises receive downconverting means adapted to receive a satellite signal via the transmit-receive connection means and to process them into a form for connection to a handset using a flexible cable. Transmit modulation and amplifying means are also provided for receiving complex modulating signals from the handset using the flexible cable and for upconverting them and amplifying them for transmission using the directional antenna to the satellite.